About the value of CRF!

[Valentin98]

Hi can anyone help me with some advice please? I want to convert a video file and I don't know what CRF bit value to use for good video quality
H.264 / AVC CFR 30 video value or H.264 / AVC CFR 20 video value?


Other details about my project: Video Export -1920x1080p / 25FPS / bitrate-10,000kbps (Mbps 10.1) / Audio 128kbps!

One more thing to mention: This project will be uploaded to YouTube!

[DB83]

One may argue that once YT get their mucky hands on a video they will re-encode it regardless of the initial quality.

That being said, a CRF (Constant Rate Quality) of 18 - 20 should give you accetable results. The issue with CRF is that you can not anticapate the final size except that the selection should give you a better quality than a randomly selected bitrate.


Personally, I wil re-encode at CRF 20 as a mean compromise between low quality and high. Bearing in mind that your source may already have been comprimised by too low a birate which you can never recover regardless.

[pandy]

One more thing to mention: This project will be uploaded to YouTube!

Then it will be recompressed to somewhere around crf = 28..32 - forget about pushing quality - use fast preset and crf around 16 - file will be big but YT will recompress it anyway.

[emcodem]

bitrate-10,000kbps (Mbps 10.1)

If you need to gain a constant bitrate which is usually desired for web streaming and hardware decoding you cannot use crf.
Also for high quality non live stuff, you should use 2-pass anyways and the highest available quality preset, e.g. veryslow

[VoodooFX]

There are some tricks used like adding a bit of noise/grain to video to "protect" it from Youtube's over-compression.
And what pandy said.

[manono]

If you need to gain a constant bitrate which is usually desired for web streaming and hardware decoding you cannot use crf.
Also for high quality non live stuff, you should use 2-pass anyways and the highest available quality preset, e.g. veryslow

This post is nonsense. DB83 and pandy suggested how to do it right. For your audio you said 128kbps. I assume that's AAC audio. I usually go with 160. Maybe overkill but, as mentioned, YouTube's going to reencode and degrade it anyway so I like to give it decent quality to begin with.

[themaster1]

I usually go with 160. Maybe overkill but, as mentioned, YouTube's going to reencode and degrade it anyway so I like to give it decent quality to begin with.

You're doing it wrong then you'd have to pick a multiple of 128 for best results so 256

[Skiller]

Really, why is that?

[pandy]

I usually go with 160. Maybe overkill but, as mentioned, YouTube's going to reencode and degrade it anyway so I like to give it decent quality to begin with.

You're doing it wrong then you'd have to pick a multiple of 128 for best results so 256

Please explain, you triggered my curiosity - thank you in advance!

[emcodem]

This post is nonsense.

Needs explaination otherwise its a useless comment.

[manono]

Needs explaination otherwise its a useless comment.

1. We don't know whether or not he originally encoded it as CBR. Maybe he did, maybe he didn't.
2. CBR is not 'desired' for web streaming and decoding. This is for YouTube and YouTube itself uses CRF VBR encoding.
3. You can use CRF.
4.

Also for high quality non live stuff, you should use 2-pass anyways...

Simply not true. You save a lot of time and get equally good quality when the average bitrate of a CRF encode is the same as that of a 2-pass VBR encode. And CBR encodes might waste bits in low complexity scenes and not have enough bits for complex scenes. This is all basic stuff.

Your whole post was made up of misinformation. Is that enough explanation for you?